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Questions tagged [tic-tac-toe]

Puzzles centered around tic-tac-toe (a.k.a. noughts and crosses).

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11 votes
1 answer
1k views

Pigpen Tic-Tac-Toe

This puzzle is part of the Monthly Topic Challenge #3: Pencil and Paper Games Introducing a new tic-tac-toe variant of my own devising (at least I haven't found an equivalent anywhere online). ...
Stiv's user avatar
  • 146k
7 votes
1 answer
388 views

Noughts and Crosses and... there's more?

Having been beaten at your favourite pencil and paper game, Noughts and Crosses, repeatedly by your friend, you decide to give up on your dreams of becoming Tic-Tac-Toe world champion. However you ...
Beastly Gerbil's user avatar
25 votes
2 answers
2k views

What is my favorite brand of pen?

This is an entry to the Monthly Topic Challenge #3: Pencil and Paper Games Given the following valid "tic-tac-toe" boards: What is my favorite brand of pen? Other possible tags to check ...
Amoz's user avatar
  • 27.7k
4 votes
1 answer
459 views

Tic-Tac-Toe on a Rubik's Cube

12 friends decide to play Tic-Tac-Toe on the surfaces of an opened Rubik's Cube which looks like this: When closed, the orientation of this Rubik's Cube is as follows: Surface Colour Up White Down ...
chandanr777 's user avatar
13 votes
2 answers
811 views

Decision Paralysis

This puzzle is part of the Monthly Topic Challenge #1: Restricted Title: xkcd 1xxx and is based on https://xkcd.com/1801/. Protip: If you ever need to defeat me, just give me two very similar options ...
noedne's user avatar
  • 15.4k
6 votes
2 answers
252 views

What is the ideal strategy in this randomised-goal tic-tac-toe variant?

In an SMBC comic published on 20 June 2022, Zach Weinersmith proposes the following variant of tic-tac-toe: Play consists of a number of rounds At the start of each round, each player rolls a d6 in ...
AakashM's user avatar
  • 161
3 votes
1 answer
244 views

Harary's generalized Tic-Tac-Toe; Winning strategy for Skinny on a 7 x 7 board?

Disclaimer: The purpose of this post is a ask question, not to offer a puzzle. Still, there are some puzzles here for the reader's pleasure. Disclaimer 2: This question was also asked on Math Stack ...
Mike Earnest's user avatar
  • 32.5k
19 votes
1 answer
2k views

Blindfold Tic-Tac-Toe

You are playing the classic game of 3x3 Tic-Tac-Toe. You are blindfolded and you cannot see the grid, while your opponent can see it. When making a move you call out a cell. If that cell is taken you ...
Dmitry Kamenetsky's user avatar
5 votes
1 answer
267 views

Playing tic-tac-toe by submitting your moves in advance

Suppose that, instead of playing in your turn, you have to submit in advance, an ordered list of the 9 board positions. Then a computer plays for you by using, whenever it is your turn, the leftmost ...
Erel Segal-Halevi's user avatar
1 vote
0 answers
767 views

How do you force a win in 4x4x4 TicTacToe

I have read in the wikipedia page of TicTacToe that it is possible for the first player to force a win in a 4x4x4 board. I tried to find a strategy on how to do it online but failed. So, how do you ...
Puzzlees's user avatar
  • 756
10 votes
2 answers
672 views

Buzzword Bingo Boss Battle!

Two bosses of different companies take turns delivering long speeches. Every speech much “claim” at least one unused square by uttering the corresponding buzzword(s) in the table below. Victory is ...
happystar's user avatar
  • 7,664
18 votes
1 answer
626 views

Noughts and Crosses puzzle

Eques and Knott are playing a game of standard 3x3 Noughts and Crosses. At no stage of the game has Eques threatened to complete a row of three on his very next turn. Suddenly Knott realises he must ...
happystar's user avatar
  • 7,664
12 votes
0 answers
469 views

Quantum tic tac toe strategy

Most of us learn tic tac toe early in our life. Also, it is easy to find an optimal strategy for playing. How about Quantum tic tac toe? What is the optimal strategy for playing it? Rules On a ...
George Menoutis's user avatar
2 votes
0 answers
116 views

Given a width of tic-tac-toe board, what is the smallest dimension such that X is guaranteed a winning strategy [duplicate]

The title says it, I'm stuck on this question.
Gynaecide's user avatar
7 votes
1 answer
1k views

Tic-Tac-Toe problem

In an infinite grid of regular triangles, Niels and Henrik are playing a game they made up. Every other time, Niels picks a triangle and writes × in it, and every other time, Henrik picks a triangle ...
khioloud Elbadry's user avatar
16 votes
2 answers
2k views

Tic-Tac-Toe Without a Predefined Board

On a warm and uneventful summer day, John and Mary passed the time by playing games of Tic-Tac-Toe, taking sticks and drawing in the soil. John and Mary are both child prodigies, so within two rounds ...
greenturtle3141's user avatar
11 votes
1 answer
740 views

A Tic-Tac-Toe variant with three marks - winning strategy and chances

We start with a usual $3 \times 3$ grid, $3$ different marks (say, $X, O, I$) and $2$ players. Player $A$ has to make a vertical, horizontal or diagonal line made of $3$ identical marks (XXX, OOO or ...
Yuriy S's user avatar
  • 1,007
1 vote
0 answers
154 views

Tic Tac Toe and random turn puzzle [closed]

I have a problem: There is a bag of 75 balls with 15 Red and rest Blue. I pick 4 balls at the start of every turn.If I get to pick at least 1 red ball, I fill 1 cell with X. If I get 3 red balls ...
MogambO's user avatar
  • 21
8 votes
1 answer
1k views

Tic Tac Toe Recursive

Related: Connect 4 Recursive We have a mega tic tac toe grid. Each of the nine cells of the mega grid has a smaller tic tac toe grid. In total we have 81 cells that can be filled. (Maybe imagine a ...
ghosts_in_the_code's user avatar
-3 votes
2 answers
913 views

Optimal running-time tic-tac-toe algorithm

A perfect tic-tac-toe AI/algorithm would ideally never lose, but only win or draw, 100% of the time. Imagine that you play against once such algorithm, and it calculates the next move to make. Is ...
Buffer Over Read's user avatar
21 votes
2 answers
1k views

Titanicker Tic-Tac-Toe

This is something of a follow-on to Hugh Meyer's enjoyable "Titanic Tic-Tac-Toe." Fortunately, our intrepid heroes Xavier and Oliver have wrested away a bit of wreckage that some fellow named Jack was ...
Matt's user avatar
  • 794
36 votes
1 answer
2k views

Titanic Tic-Tac-Toe

Xavier and Oliver were playing tic-tac-toe on the Titanic using a wooden board and metal X's and O's. As the stern of the ship sank lower and lower they found, to their annoyance, that the pieces ...
Hugh Meyers's user avatar
  • 23.8k
2 votes
1 answer
413 views

Another Tic-Tac-Toe problem

Two players A and B play Tic-Tac-Toe on an infinite 3-dimensional grid. Player A starts first and uses X, player B plays second and uses O. Every time player A places an X on the grid, player B can ...
Puzzle Prime's user avatar
  • 6,964
15 votes
2 answers
2k views

Tic-Tac-Toe variant

To help people think this out, I've made a web game with increasingly difficult cpu players to allow brainstorming and testing strategies: cpu player, easiest (version 1 - at least 5-in-a-row is ...
MWilliams's user avatar
  • 1,058
15 votes
2 answers
1k views

Devising a sudoku where the rows are the moves for a draw in tic tac toe

The task is to construct a sudoku whose rows (or columns) are the moves for a game in tic tac toe where the game ends in a draw. Here are some clarifications and constraints which should limit ...
Rohinb97's user avatar
  • 909
15 votes
3 answers
1k views

N-dimensional Tic-Tac-Toe variant

Consider the game surface to be an infinite N dimensional Cartesian lattice. The rules are X moves first, but O gets to move ...
MWilliams's user avatar
  • 1,058
12 votes
3 answers
3k views

Tic-tac-toe 1000 in a row

Consider a variant of Tic-Tac-Toe and Gomoku on a board that's infinite in every direction. X wins by getting a line of 1000 X's ...
xnor's user avatar
  • 27.4k
6 votes
2 answers
2k views

What is the smallest tic-tac-toe board to have a winning strategy?

There is not winning strategy for 9cell 3x3 board. There is a winning strategy for 16cell 4x4 board, or even for 10cell "3x3 + 1_cell_near_a_corner" board (see M.Gardner "Mathematical games"): $$ \...
klm123's user avatar
  • 16.3k
42 votes
6 answers
25k views

What is the optimal first move in tic-tac-toe?

I have been told that it is possible to guarantee no worse than a tie in normal 3x3 tic-tac-toe, but that the first move is very important. What is that important first move?
Xynariz's user avatar
  • 3,620